Recently, there have been a number of comments on the rpml relating to a promotional part given out by Ciba and 3D Systems at the recent 3D Systems North American Stereolithography User's Meeting in San Antonio. We would like to describe this part (for those of you who did not attend) and provide some insight into why the samples where given and what expectations we have for the material.
Earlier this year, we presented a new resin to 3D Systems designed to be used in snap fit and dynamic assembly applications. The material exhibits characteristics of durability and flexibility, while showing sufficient rigidity to make it useful in snap fit applications. This new resin has excellent humidity resistance, good sidewall finish and good accuracy. The material is also optically transparent, allowing for visualization and it appears useful in photoelastic stress applications. The material was well received at 3D and an aggressive program was put into place to determine commercial viability. As testing evolved, it became clear that this material was very user friendly and performance was consistent with our presentation to 3D. At this point in time, we decided to provide 3D's stereolithography customers with an early view of this new material. It was also at this time, that the designation of ABS/Proto was created for this durable resin.
Prior to our decision to make give away parts out of the durable resin for the user meeting, we had the opportunity to make a number of assemblies for customers. This gave us a chance to evaluate the materials performance in real life situations. One such part involved four snap fit clips in a four component assembly. The parts were made and assembled with great success. A like collection of parts made out of SL 5170 would not assemble without breakage. To date, this assembly made with ABS/Proto has successfully undergone over 100 reassemblies without a failure. Given this success along with others, we felt that the material was promising enough to provide a sample to the customer. The task was then, how do we sample the customer with the durable resin parts.
A decision was made in February to create a give away part that highlighted different types of snap fit assemblies. CAD work was done, parts were built, finished and packaged for the meeting. The give away part (stop sign assembly) was a three-piece assembly including a snap fitting cylinder and base. These two parts highlighted the "click" type of snap fit commonly found in commercial products. A third part was a stop sign post that snapped into the base and allowed for flexing through a window in the cylinder/base structure. This allowed the user's to test the flexibility of the resin. The schedule for accomplishing this task of design through manufacture was very aggressive. We understood the risks in attempting to promote a new concept in this fashion, but felt that the message provided the user's was important enough to take risks.
Since the parts where given out at the meeting, a number of comments about the durable resin have been noted on the rpml. All have focused on failure while applying dynamic load. To further add to the discussion, we would like to share some observations we have on the durable resin:
a) 25% elongation to break. A five fold increase over products like Cibatool‚SL 5410/5510 and SOMOS 7100/7120.
b) Izod impact strength of 1 ft lb/inch. A two fold increase over products like Cibatool SL 5410/5510 and SOMOS 7100/7120.
c) 30 day aging of durable resin parts showed NO significant change in elongation and impact strength, the key material properties for demonstrating durability and flexibility. Thermal aging continued to show good retention of these properties.
d) There were design issues with the stop sign part, such as no draft angles on the signpost and excessively heavy clips on the cylinder/base assembly. We believe that these issues allow for stress concentrations, significantly contributing to early failure of the parts.
e) The fabrication and performance of so many durable resin parts has given us excellent insight into how build orientation, post processing and part design affect overall performance. Many of the things we learned, if now applied, would result in more robust assemblies. This knowledge will become part of the package, as materials like this are offered on the market.
Ciba and 3D are very excited about the possibility of supplying a new resin with performance characteristics like those of this durable resin to 3D's stereolithography customer base. By supplying an early look at such a product we are hoping to get feedback from SLA users as to what they like and don't like. This is also an opportunity for users to give us insight into their material needs for present and future applications. Ciba and 3D welcome not only the comments regarding failure of the stop sign, but also any other impressions of the material and suggestions for future improvements.
We are making great strides in the development of dynamic use, stereolithography resins. Your feedback is critical to us as we try to bring out more and more products that provide value. In retrospect, the risk we took in supplying customers with durable resin samples was justified. We have had excellent feedback, which we will use to further direct our development activities. Regardless of how much information we have received to date, we still want more. For those of you that received a stop sign part, send me, Bob or Thomas your impressions and wish lists, we will make good use of your responses.
Ed Clark, Market Director
Bob Kruger, Product Manager
Thomas Pang, Technical Manager
Ciba Specialty Chemicals
5121 San Fernando Road West
Los Angeles, CA 90039
(818) 507-0167 fax
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